That location information is stored here until the photo's owner approves (or rejects) the suggestion. If approved, the photo is geotagged on Flickr (using the Flickr API) and the suggestor is credited by adding a special tag to the photo.

Opting-out means that you'd rather not participate at all and other
Flickr users will be prevented from suggesting locations for your photos.

Either way, you will be redirected to Flickr.com first to confirm that you want to allow this website to suggest locations on your behalf (or to prevent other people from suggesting locations for your photos). You should only need to do this once.